[Klavoir]

Hi,

I am simulating heat tranfer via a hot air stream through a steel pipe which is enclosed by water. The steel pipe has vertical tubes to increase heat transfer from the air to the water. I used a non conformal mesh so that I can mesh the tubes in detail without having a lot of cells in the water region. I also modeled the thickness of the steel pipe as a seperate zone.
I see I get a lot of so called contact regions under boundary conditions in Fluent, which in fact are walls. I run a simulation and heat seems to be transported because the air is cooled flowing through the pipe. However, when I look at the thermal boundary condition of the contact regions it has the default heat flux = 0 value.
How is it possible there is heat transfer. Should I use System coupling in stead?
It is very confusing to me what is going on here, what is exactly this contact region?